South of
Lower on the grid than the referenced person or object.
Explanation
South of means strictly below on the grid — the suspect must be in a row with a higher number than the reference. It does not require being in the same column or region.
Example
If a clue says 'Anna is south of the bookshelf,' Anna must be placed in a row below the bookshelf's row. The column does not matter unless further restricted.
Common Mistake
Players sometimes treat south of as requiring the same column (directly below). That is incorrect — any cell in a lower row qualifies.